PowerPoint PresentationSlide 2Slide 3Slide 4Slide 5Slide 6Slide 7Slide 8Slide 9Slide 10Slide 11Slide 12Slide 13Slide 14For MondayOther influences on traits – Chpt 4 section 4.12, 4.131)Sex limited vs. sex influenced traits2)Penetrance3)Expressivity4)Others…5)MORE PROBLEM REVIEW!Top 4 for Friday, Sept. 20, 2013Sex Linkage (Chpt. 4) and Pedigrees revisited (Chpt. 3 and 4)Sex Linkage – Chpt 4 section 4.111) Inheritance2) Human X-linkagePedigrees – Chpt 3 section 3.9 and Chpt 4 section 4.111) Autosomal pedigrees2) Sex-linked pedigreesSex linkageThe condition of unlike chromosomes- in many animal and some plant speciesInvolved in sex determination (in some way)Often indicated XY (or in birds, butterflies, moths – ZW)Humans/Drosophila – female XX, male XYBirds, butterflies, moths – male ZZ, female ZWY/W contains region of homology with X/Z but much of these smaller chromosomes are blank genetically – as a result genes on X/Z have inheritance different than autosomal genesX-linkage Z-linkageDetermine sex linkage with a reciprocal crossAutosomal trait:cinnabar gene in Drosophilacn+ = dominant for wildtype eyescn- = recessive for orange eyescinnabar x wildtypeF1 – 100% wildtypeF2 – 3:1 wildtype:cinnabarcinnabar x wildtypeF1 – 100% wildtypeF2 – 3:1 wildtype:cinnabarX-linked trait:white eye gene in Drosophilaw+ = dominant for wildtype eyesw- = recessive for white eyeswhite x wildtypeF1 – 100% wildtypeF2 – males 1:1 wildtype:white females all wildtypewhite x wildtypeF1 – females wildtype males whiteF2 – males 1:1 wildtype:white females 1:1 wildtype:white-criss-crossed pattern of inheritance – where phenotypic traits controlled by recessive X-linked genes are passed from homozygous mothers to all sons.-Y lacks homology with X – whatever alleles present on X will be expressed in male phenotype-Males called hemizygous – cannot be heterozygous or homozygous for X-linked genesPrevious Exam Question:In pigeons, the recessive opal gene, o, controls a wing pattern that appears checkered. This gene has two alleles, the dominant allele produces no checkered pattern and the recessive allele produces checkers. Design an experiment to test whether the opal gene is autosomal or sex-linked. (Hint: remember birds follow a ZZ/ZW system of sex chromosomes)What results would support the sex-linked hypothesis?What results would support the autosomal hypothesis?Best way to understand trait transmission in humans – use pedigreesUsed to determine pattern of expression of genes and mode of inheritancePedigree for myopia (near-sightedness). Is this disorder the result of a dominant or recessive trait? What are most probable genotypes?From page 63.Previous exam question:Examine the following pedigrees and describe what kind of disorder each depicts (autosomal or X-linked, recessive or dominant). Give potential genotypes for individuals 1 and 2 in generation I.a. b.Previous exam question:A woman claims that her baby boy was fathered by a famous man. Her blood type is A, his is B, and the baby is O. The baby has X-linked hemophilia and the woman claims that the father passed this trait on to his son because that disease is found in his family. She is planning a very large lawsuit. Imagine that you are a genetic counselor advising this woman about her claims. Based on blood type, could this man be the baby’s father? (give the possible parent and baby genotypes)What could you tell this woman about her claims that her child inherited hemophilia from his father? Explain your